From 3e00bf91fefced104ba91721674efe4502cb416a Mon Sep 17 00:00:00 2001 From: Xin Long Date: Fri, 18 Aug 2017 11:01:36 +0800 Subject: [PATCH] net: sched: fix NULL pointer dereference when action calls some targets [ Upstream commit 4f8a881acc9d1adaf1e552349a0b1df28933a04c ] As we know in some target's checkentry it may dereference par.entryinfo to check entry stuff inside. But when sched action calls xt_check_target, par.entryinfo is set with NULL. It would cause kernel panic when calling some targets. It can be reproduce with: # tc qd add dev eth1 ingress handle ffff: # tc filter add dev eth1 parent ffff: u32 match u32 0 0 action xt \ -j ECN --ecn-tcp-remove It could also crash kernel when using target CLUSTERIP or TPROXY. By now there's no proper value for par.entryinfo in ipt_init_target, but it can not be set with NULL. This patch is to void all these panics by setting it with an ipt_entry obj with all members = 0. Note that this issue has been there since the very beginning. Signed-off-by: Xin Long Acked-by: Pablo Neira Ayuso Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/act_ipt.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/sched/act_ipt.c b/net/sched/act_ipt.c index a1aec0a6c789..50030519a89b 100644 --- a/net/sched/act_ipt.c +++ b/net/sched/act_ipt.c @@ -41,6 +41,7 @@ static int ipt_init_target(struct xt_entry_target *t, char *table, { struct xt_tgchk_param par; struct xt_target *target; + struct ipt_entry e = {}; int ret = 0; target = xt_request_find_target(AF_INET, t->u.user.name, @@ -51,6 +52,7 @@ static int ipt_init_target(struct xt_entry_target *t, char *table, t->u.kernel.target = target; memset(&par, 0, sizeof(par)); par.table = table; + par.entryinfo = &e; par.target = target; par.targinfo = t->data; par.hook_mask = hook;